Table of Contents
Item 6: Elm Best Practices - Avoid creating unnecessary objects
In Elm, like in many programming languages, creating unnecessary objects can lead to increased memory usage, slower performance, and less efficient code. Elm's functional nature encourages immutability and pure functions, which inherently reduce the need for creating and managing objects. However, there are still scenarios where developers might inadvertently create more objects than necessary. By following best practices to avoid creating unnecessary objects, you can write cleaner, more efficient, and performant Elm code.
Why Avoid Creating Unnecessary Objects in [[Elm]]?
Avoiding unnecessary object creation in Elm offers several key benefits:
1. **Improved Performance**: Fewer objects mean less memory allocation and garbage collection, leading to faster and more responsive applications. 2. **Simplified Code**: Reducing unnecessary object creation results in simpler, more readable code that's easier to maintain. 3. **Optimized Resource Usage**: By minimizing object creation, you reduce the overall resource footprint of your application, making it more scalable.
Example 1: Reuse Data Structures Instead of Recreating Them
One common scenario where unnecessary objects might be created is when you repeatedly create identical data structures instead of reusing them.
- Creating Unnecessary Data Structures (Anti-Pattern)
```elm module Main exposing (..)
import Html exposing (Html, text)
– Function that creates the same data structure multiple times createList : Int → List Int createList n =
List.repeat n 1
main =
let
list1 = createList 10
list2 = createList 10
in
text (String.fromInt (List.length list1 + List.length list2))
```
In this example, the `createList` function creates a new list of identical elements every time it's called. This results in multiple lists with the same content, which is inefficient.
- Reusing Data Structures
```elm module Main exposing (..)
import Html exposing (Html, text)
– Function that reuses the same data structure createList : Int → List Int createList n =
let
sharedList = List.repeat n 1
in
(sharedList, sharedList)
main =
let
(list1, list2) = createList 10
in
text (String.fromInt (List.length list1 + List.length list2))
```
In this improved version, the list is created once and reused, avoiding unnecessary object creation and reducing memory usage.
Example 2: Avoid Redundant Transformations
Another common scenario where unnecessary objects might be created is when applying redundant transformations to data, leading to the creation of intermediate objects that aren't needed.
- Redundant Transformations (Anti-Pattern)
```elm module Main exposing (..)
import Html exposing (Html, text) import String
– Function that performs redundant transformations processString : String → String processString str =
let
uppercased = String.toUpper str
trimmed = String.trim uppercased
in
trimmed
main =
text (processString " hello world ")```
In this example, the string is first converted to uppercase and then trimmed, creating unnecessary intermediate strings.
- Combining Transformations
```elm module Main exposing (..)
import Html exposing (Html, text) import String
– Function that combines transformations processString : String → String processString str =
String.trim str ]] | [[> String.toUpper
main =
text (processString " hello world ")```
In this improved version, the transformations are combined in a more efficient way, avoiding the creation of unnecessary intermediate objects.
Example 3: Use Lazy Evaluation When Possible
Elm is not a lazily evaluated language by default, but there are cases where you can manually implement lazy evaluation patterns to avoid unnecessary computations and object creation.
- Eager Evaluation Leading to Unnecessary Objects (Anti-Pattern)
```elm module Main exposing (..)
import Html exposing (Html, text)
– Function that eagerly evaluates a list computeSum : List Int → Int computeSum numbers =
List.foldl (+) 0 numbers
main =
let
largeList = List.range 1 1000000
sum = computeSum largeList
in
text (String.fromInt sum)
```
In this example, the entire list is created and passed to the `computeSum` function, which eagerly evaluates it.
- Implementing Lazy Evaluation
```elm module Main exposing (..)
import Html exposing (Html, text) import Lazy
– Function that uses a lazy evaluation approach computeSum : Int → Lazy.Lazy Int → Int computeSum 0 _ = 0 computeSum n lazySum =
Lazy.force lazySum + n
main =
let
largeList = List.range 1 1000000
lazySum = Lazy.lazy (\() -> List.foldl (+) 0 largeList)
sum = computeSum 1000000 lazySum
in
text (String.fromInt sum)
```
In this improved version, lazy evaluation is implemented to delay the creation of the large list until it's absolutely necessary, reducing unnecessary memory usage.
When to Avoid Creating Unnecessary Objects in [[Elm]]
Avoid creating unnecessary objects in the following scenarios:
- **Reusing Data Structures**: When you can reuse data structures instead of recreating them, do so to save memory and improve performance. - **Avoiding Redundant Computations**: Combine operations and avoid redundant transformations to reduce the creation of intermediate objects. - **Implementing Lazy Evaluation**: Where possible, use lazy evaluation techniques to avoid creating objects or performing computations until they are actually needed.
Conclusion
In Elm, avoiding unnecessary object creation is a best practice that leads to better performance, reduced memory usage, and cleaner, more maintainable code. By reusing data structures, avoiding redundant transformations, and implementing lazy evaluation where appropriate, you can optimize your Elm applications for efficiency and scalability.